Texas Electrician ExamTexas journeyman & master

Checked against primary sources 2026-08-24

A cow bridges the floor and the waterer at the same time

Two hazards drive this article and only one of them is about people. Know what the atmosphere does to hardware and what a small voltage does to an animal, and the requirements stop looking arbitrary.

On this page
  1. Does Article 547 apply at all?
  2. What the atmosphere does to the hardware
  3. Why an animal feels what a person does not
  4. The equipotential plane, and what it bonds to
  5. The pool grid and the farm plane are not the same rule
  6. Supply from a distribution point
  7. Ground-fault protection in a barn
  8. The addresses in this article have moved
  9. What this is worth on the paper
  10. Before you sit
  11. What this page cites

Does Article 547 apply at all?

Usually not to the whole farm, and that is the first thing an item tests.

The article is written around conditions, not around ownership or zoning. NEC 547.1 names the conditions, which come down to dust from feed and bedding, a corrosive atmosphere off animal waste and the chemicals used to clean up after it, and areas kept wet by periodic washing. Where those conditions are absent, so is the article.

For buildings and structures not having conditions as specified in 547.1, the electrical installations shall be made in accordance with the applicable articles in this Code.

NEC 547.5

That sentence is the whole scope test, and it is doing more work than any requirement in the article. A farm office with a desk in it, a farmhouse, a machine shed used for parking a tractor: no dust, no ammonia, no washdown, no Article 547. Chapters 1 through 4 govern them the way they govern a strip mall.

The code says as much a second time, from the other direction. NEC 547.28 sends you to 210.8(B) for ground-fault protection in the areas of an agricultural building that fall outside this article's scope, which only makes sense if an agricultural building routinely contains areas the article does not reach.

So the reading order is fixed. Decide whether the described conditions exist. Only then open the requirements.

What the atmosphere does to the hardware

Ammonia and hydrogen sulfide off manure attack metal continuously, and nobody notices until a fitting crumbles in a hand.

Corrosion in a confinement barn is not the slow surface rust of an outdoor disconnect. It goes after the parts that hold a connection together, and it works inside an enclosure as happily as outside it. A raceway corroded through has lost its mechanical protection, and if it was carrying a grounding path it has lost that too.

The moisture side gets its own section, and the wording is worth reading because it covers a case people miss. NEC 547.23 treats a normally dry or damp area that gets periodically washed or sprayed with water as a wet location, which means boxes, conduit bodies, fittings and equipment enclosures in it have to be listed for wet locations and the enclosures have to be weatherproof. Hosing down a pen once a week is enough to put you there.

The same section handles the ordinary case: in damp or wet locations, enclosures, boxes, conduit bodies and fittings are placed or equipped so moisture cannot get in or collect inside, per NEC 547.23.

Heat is separate again. NEC 547.4 governs surface temperatures, because dust that settles on a warm surface is a fire problem long before it is an explosion problem.

Do not confuse any of this with classified locations. Feed dust is combustible, and an area can be dusty without being classified. Where a location does get classified, the requirements come out of Article 500 and its neighbors and Article 547 stops being the controlling article.

Why an animal feels what a person does not

A cow makes contact with the ground over four wet hooves spread across several feet of floor, and with metal through a wet muzzle. A person makes contact through boot soles a few inches apart and a dry hand.

That difference is the whole reason this article has a requirement nothing else in the book has. The animal is bridging two points on the floor and a piece of metal at once, with no insulation anywhere in the path and a lot of moisture in it. A potential difference that a person would never register sits across the animal continuously.

It shows up as behavior first. Michael Johnston, writing in Electrical Contractor Magazine, describes neutral-to-earth stray current as causing behavior problems, loss of production and death in farm animals, and the trade calls the small voltages involved tingle voltages. Animals stop drinking, refuse a stall, and milk yield falls, months before anybody thinks to call an electrician.

Hold that picture and the next section writes itself.

The equipotential plane, and what it bonds to

It is a conductive element in or under the floor, tied to the metal the animal can reach, so there is no difference between the hoof and the muzzle.

NEC 547.44(A) is where it goes. Indoors, an equipotential plane is required in confinement areas with concrete floors where metallic equipment that could become energized is accessible to livestock. Outdoors, the same requirement lands on concrete slabs under the same condition. The plane has to cover the area where the animal actually stands while reaching that equipment, not merely exist somewhere in the room.

NEC 547.44(C) is what it is made of, and the cheap answer is usually already in the slab: unencapsulated structural reinforcing steel, bonded together with steel tie wires or the equivalent. Unencapsulated welded wire reinforcement embedded in the surface material works too. Where the steel is missing, or encapsulated in something nonconductive, or cannot be embedded, the section falls back to a bare solid copper grid on a twelve inch square pattern laid directly under the surface material.

Then the part everybody gets wrong.

Equipotential planes shall be bonded to the grounding electrode system or an equipment grounding terminal in any enclosed panelboard of the electrical grounding system associated with the equipotential plane. The bonding conductor shall be solid copper, insulated, covered or bare, and not smaller than 8 AWG.

NEC 547.44(B)

Read that twice. The plane is not left floating at a potential of its own. A conductor is deliberately run from it to the grounding electrode system, or to an equipment grounding terminal in an enclosed panelboard. Solid copper. Insulation is optional. The size floor is written into the section, so read the whole of 547.44 in your own book and do not take any of it from a summary.

The reason is the same reason the plane exists. A conductive floor sitting at a different potential from the building's grounding system would put that difference across the first animal to touch both, which is precisely the hazard the plane was installed to remove. Bonding it to the grounding system is what makes the floor and the metal one potential instead of two.

The pool grid and the farm plane are not the same rule

They solve the same physics and the code writes them differently, which is exactly the kind of pair an item is built from.

At a pool, NEC 680.26(B) does not require the bonding conductors to be extended or attached to remote panelboard enclosures, to service equipment, or to electrodes. The connection to the premises equipment grounding system happens anyway, at the pump, because the pump is a bonded part and it is also fed by a branch circuit with an equipment grounding conductor landed on it.

In a barn, NEC 547.44(B) does not leave that to chance. It names the destination and makes you run a conductor to it.

So if you carry one sentence into the room, make it this: both networks end up tied to the grounding system, and only Article 547 makes you install a conductor to get there. An answer choice claiming the farm plane stands apart from the electrical grounding system is wrong. An answer choice sending the pool grid back to a panelboard or an electrode is also wrong. Same idea, two articles, opposite wording.

Supply from a distribution point

A farm is a yard pole with a meter on it and then five or six structures fanning out, plus a well, plus a grain dryer, plus whatever got added in 1994.

The code calls the place the supply splits the distribution point and it is a defined idea, not a description. NEC 547.40 requires any agricultural building or structure for livestock on the premises to be supplied from a distribution point.

Note the reach of that. It is livestock buildings, not every structure on the farm, and this is another place where the article covers less than people assume.

Note also what it does not say. NEC 547.40 permits more than one distribution point on the same premises, so the picture of a single handle that kills an entire farm is not the rule. A large operation can have several, and an item describing one yard pole feeding everything is describing one common arrangement, not a requirement.

The sections around it carry the rest of the arrangement. NEC 547.41 deals with the service disconnecting means and overcurrent protection at each building or structure, and with the site-isolating device. NEC 547.42 deals with the disconnecting means and overcurrent protection back at the distribution point itself. Grounding and bonding at each building downstream ties into 250.32, which is where a surprising number of these items actually land.

An item in this area usually describes a yard pole feeding several structures and then asks about the disconnect, about grounding at one of the buildings, or about the grounded conductor on the way there. Knowing that the distribution point is a defined term gets you to the right page.

Ground-fault protection in a barn

Two different rules live in one short section, and mixing them up is an easy point to lose.

NEC 547.28 handles the parts of an agricultural building this article does not reach by pointing at 210.8(B), which is the ordinary rule for other than dwelling units. Nothing special happens there.

Inside the article's scope, the protection is aimed at ordinary 125-volt, 15- and 20-ampere receptacles in the places where an animal or a person is standing in water or on a plane: areas requiring an equipotential plane, outdoors, damp or wet locations, and dirt confinement areas for livestock. Read the exact list in 547.28 in your own copy, because the wording is negative and it is easy to invert.

The distinction worth carrying is that Article 547 does not replace the general GFCI rule. It adds locations to it and hands the rest back.

The addresses in this article have moved

If your notes say 547.9 for the distribution point and 547.10 for the equipotential plane, they are describing a book that is no longer on the shelf.

In the 2026 edition the supply and disconnect rules sit at 547.40 through 547.42 and the equipotential plane sits at 547.44. The wiring and installation material lives in the 547.20s, which is where 547.23 and 547.28 come from.

Almost everything published about this article on the open web still uses the old addresses, including good material from EC&M and from Electrical Contractor Magazine. That does not make the substance wrong, it makes the navigation wrong, and in an open-book exam navigation is the part that costs you minutes.

The habit that survives an edition change is to find requirements by part title and heading rather than by remembered address. It is slower on an article you know and much faster on one you do not.

What this is worth on the paper

Special Occupancies, Equipment, and Conditions is 6 of the 56 scored items on the journeyman NEC Knowledge portion and 3 of the 24 scored items on Calculations, per the PSI bulletin. Article 547 shares that pool with marinas, health care, pools, hazardous locations and the rest of Chapter 5, so you are not going to see a page of farm questions.

What you are likely to see is one item, worded so the scope decision is most of the work.

None of that needs farm experience. It needs forty minutes with the article and a clear head about the scope.

Before you sit

  1. Read 547.1 and 547.5 together and mark them. The scope and the sentence that hands everything else back to the general chapters are the most tested lines in the article.
  2. Read 547.44 end to end, then go and read the pool bonding section and write down, in your own words, how the two differ on what gets connected to what.
  3. Mark 547.40 through 547.42 as a block, and read 250.32 alongside them.
  4. Skim 547.23 and 547.28 once. Both are short and both are built for one-line items.
  5. Leave the rest. There is far more in this article than a journeyman paper will reach for, and the hour is better spent on branch circuits.

For anyone sitting on or after 1 September 2026, the edition changes that day: Texas adopts the 2026 National Electrical Code under 16 TAC 73.100 and the examinations move with it.

What this page cites

NEC and National Electrical Code are registered trademarks of the National Fire Protection Association.

Trojan Digital Marketing is an independent company. We are not affiliated with, endorsed by, or sponsored by NFPA, TDLR, PSI Services, or any licensing authority.

Bring your own current copy of the National Electrical Code. The Texas exam is open book.

All practice questions are original. They are not actual exam questions.

Built and maintained by Jeff Clerisier, Trojan Digital Marketing.

Every rule here is cited to the section it comes from, and corrections are logged in public with the date. This is study material rather than electrical advice, and it does not replace your own code book or your inspector.